The disclosure is directed to an electro-pneumatic actuator, such as a positioner or an I/P transducer array, for a field device of a processing plant, such as a brewery, a petrochemical plant or the like. Such an electro-pneumatic actuator is generally designed to output a pneumatic drive actuating signal to a pneumatic drive, so as to set a final controlling device, such as a control valve, of the field device. The electro-pneumatic actuator can include a pneumatically operated display for displaying at least one field device-specific operating information.
For example, one such known display takes the form of a pneumatically actuated indicator for visually displaying the position of a pneumatically actuated valve, which is used for opening or closing a fluid line. The valve has a pneumatic drive with a working chamber, which can be exposed to a drive pressure that counteracts a spring preload, so as to move a drive piston for actuating the valve. The visual indicator is screwed into a thread in the drive piston of the drive, so as to track the movement of the drive piston. The visual indicator visually displays whether the pneumatic drive has been exposed to the drive pressure or not.
The exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings. For the sake of better readability, similar or identical components of the exemplary embodiments are provided with the same or similar reference numbers below